#!/usr/bin/env python3
# SPDX-License-Identifier: LGPL-2.1-or-later

import collections
import glob
import pprint
import sys
from pathlib import Path

from xml_helper import xml_parse


def man(page, number):
    return f'{page}.{number}'

def add_rules(rules, name):
    xml = xml_parse(name)
    # print('parsing {}'.format(name), file=sys.stderr)
    if xml.getroot().tag != 'refentry':
        return
    conditional = xml.getroot().get('conditional') or ''
    rulegroup = rules[conditional]
    refmeta = xml.find('./refmeta')
    title = refmeta.find('./refentrytitle').text
    number = refmeta.find('./manvolnum').text
    refnames = xml.findall('./refnamediv/refname')
    target = man(refnames[0].text, number)
    if title != refnames[0].text:
        raise ValueError('refmeta and refnamediv disagree: ' + name)
    for refname in refnames:
        assert all(refname not in group
                   for group in rules.values()), "duplicate page name"
        alias = man(refname.text, number)
        rulegroup[alias] = target
        # print('{} => {} [{}]'.format(alias, target, conditional), file=sys.stderr)

def create_rules(xml_files):
    " {conditional => {alias-name => source-name}} "
    rules = collections.defaultdict(dict)
    for name in xml_files:
        try:
            add_rules(rules, name)
        except Exception:
            print("Failed to process", name, file=sys.stderr)
            raise
    return rules

def mjoin(files):
    return ' \\\n\t'.join(sorted(files) or '#')

MESON_HEADER = '''\
# SPDX-License-Identifier: LGPL-2.1-or-later

# Do not edit. Generated by update-man-rules.py.
# Update with:
#     ninja -C build update-man-rules
manpages = ['''

MESON_FOOTER = '''\
]
# Really, do not edit.
'''

def make_mesonfile(rules, _dist_files):
    # reformat rules as
    # grouped = [ [name, section, [alias...], condition], ...]
    #
    # but first create a dictionary like
    # lists = { (name, condition) => [alias...]
    grouped = collections.defaultdict(list)
    for condition, items in rules.items():
        for alias, name in items.items():
            group = grouped[(name, condition)]
            if name != alias:
                group.append(alias)

    lines = [ [p[0][:-2], p[0][-1], sorted(a[:-2] for a in aliases), p[1]]
              for p, aliases in sorted(grouped.items()) ]
    return '\n'.join((MESON_HEADER, pprint.pformat(lines)[1:-1], MESON_FOOTER))

def main():
    source_glob = sys.argv[1]
    target = Path(sys.argv[2])

    pages = glob.glob(source_glob)
    pages = (p for p in pages
             if Path(p).name not in {
                     'systemd.directives.xml',
                     'systemd.index.xml',
                     'directives-template.xml'})

    rules = create_rules(pages)
    dist_files = (Path(p).name for p in pages)
    text = make_mesonfile(rules, dist_files)

    tmp = target.with_suffix('.tmp')
    tmp.write_text(text)
    tmp.rename(target)

if __name__ == '__main__':
    main()
